By incorporating flexible bis(imidazol-1-ylmethyl)benzene (bix) co-ligands, four new racemic cobalt phosphonates with formulae Co₃(3-ppap)₂(1,4-bix)₂(H₂O)₄·4H₂O (1), Co₃(3-ppap)₂(1,3-bix)₂(H₂O)₄·5H₂O (2), Co₃(3-ppap)₂(1,2-bix)₂(H₂O)₄·4H₂O (3) and Co₃(ppa)₂(1,2-bix)₂·4H₂O (4) are isolated, where 3-ppapH₃ represents 3-phenyl-3-((phosphonomethyl)amino)propanoic acid and ppaH₃ is 2-phenyl-2-(phosphonomethylamino)acetic acid. Compounds 1–3 crystallize in the monoclinic space group P2₁/c and show two-dimensional structures in which the Co₃(3-ppap)₂ chains are bridged by 1,4-bix, 1,3-bix and 1,2-bix ligands in trans-modes, respectively. Within the chain, a racemic dimer of Co₂(3-ppap)₂²⁻ is found, where the Co atoms are doubly bridged by O–P–O units from the (S)- and (R)-3-ppap³⁻ ligands. The dimers are connected by another crystallographically independent Co atom through O–P–O linkages to form an infinite racemic chain. The packing modes of the layers in 1–3 are quite different, however, which are ABAB in the cases of 1 and 3 while ABCDABCD in the case of 2, attributed to the positional isomerism of the bix co-ligands. Compound 4 displays a chain structure in which the 1,2-bix bridges the Co atoms in cis-mode within the chain. Magnetic properties are investigated for all compounds.